diff --git a/ospf6d/ospf6_route.c b/ospf6d/ospf6_route.c
index 398acfa..5f1869a 100644
--- a/ospf6d/ospf6_route.c
+++ b/ospf6d/ospf6_route.c
@@ -304,7 +304,7 @@
   return route;
 }
 
-#ifndef NDEBUG
+#ifdef DEBUG
 static void
 route_table_assert (struct ospf6_route_table *table)
 {
@@ -350,7 +350,7 @@
 #define ospf6_route_table_assert(t) (route_table_assert (t))
 #else
 #define ospf6_route_table_assert(t) ((void) 0)
-#endif /*NDEBUG*/
+#endif /*DEBUG*/
 
 struct ospf6_route *
 ospf6_route_add (struct ospf6_route *route,